Now return AE_BAD_PARAMETER if the input register pointer is
null, and AE_BAD_ADDRESS if the register has an address of zero.
Previously, these cases simply returned AE_OK. For optional
registers such as PM1B status/enable/control, the caller should
check for a valid register address before calling.  ACPICA BZ 748.

http://www.acpica.org/bugzilla/show_bug.cgi?id=748Signed-off-by: Bob Moore <robert.moore@intel.com>
Signed-off-by: Lin Ming <ming.m.lin@intel.com>
Signed-off-by: Len Brown <len.brown@intel.com>